In recent years, out of consideration for the environment and from an economical perspective, there has been a demand for improvement in the fuel efficiency of automobiles. Against this background, there is a desire to reduce the rolling resistance of tires. Therefore, the weight of the structural components and members of tires is being reduced.
In particular, one effective way of lowering the weight of the tire is to reduce the amount of rubber used. For example, it has been proposed to lower the height of the bead filler or to make the bead filler less thick. When reducing the amount of rubber used in the bead portion by using less bead filler, however, the rigidity of the bead portion degrades dramatically, making it difficult to guarantee steering stability.
On the other hand, with regard to the side rubber near the bead portion, where much rubber is used, Patent Literature 1 proposes hollowing out a recessed portion on the lateral surface of the tire in order to reduce the amount of rubber by the volume of the recessed portion and lower the weight of the tire.